Pneumatic measuring device



Dec. 31, 1935. M. MENNESSON I PNEUMATIC MEASURING DE Original Filed July 9, 1951 FILL [Z0292 eye" Patented Dec. 31, 1935 UNITED STATES PATENT OFFICE signor to Societe Anonyme de Construction de Materiel Automobile S. A. C. M. A., Paris,

France Original application July 9, 1931, Serial No.

Divided and this application February 20, 1934, Serial No. 712,246. In Belgium September 9, 1930 4 Claims.

The present invention is a divided part of my co-pending application Serial No. 549,770 filed July 9, 1931, and relates to pneumatic measuring devices of the class described in the present inventors co-pending applications, Serial No. 334,987, filed January 25, 1929 and Serial No. 442,915, filed April 9, 1930.

The object of the invention is to provide an apparatus for measuring the internal diameter or dimensions of a hollow tubular or cylindrical piece.

The accompanying drawing shows a diagrammatic section of one illustrative embodiment of the invention. 1

Referring to the figure, there is shown an assembly composed of the following elements; a chamber I provided with a needle valve controlvling an air inlet port 2-a manometric tube 4 containing a liquid 4 and responding to variations of pressure in chamber l via a conduit 4 -an air supply tube 5 connected to a source of air pressure at 6,a pair of tubes 1 and l intercala-ted mtween conduits 5 and i and extending into a liquid 8 to two diflerent depths H and 11 a water supply conduit 9- -an overflow Ill-a conduit l2 communicating at one extremity via a port II with chamber l and at its opposite extremity with a bifurcated conduit l3l3 Discharge orifices 3 and 3 are situated at the extremities oi the bifurcated conduit l3|3 formed inside an exploring element 22, to be introduced in the hollow cylinder C, whose internal diameter or dimensions are to be measured. The

discharge orifices 3, 3 are guided to lie slightly out of contact with internal walls of cylinder C, by projections 20-21 extending somewhat beyond said orifices. The exploring element 22 may be made in form of a circular disc for exploring object C when the latter is of cylindrical form. The hereinabove described assembly operates in the following manner: Assuming water to be supplied via conduit 0 and discharged through overflow ll, air entering through conduit 6 will be fed at substantially constant pressure through port 2 into chamber I, momentary excess of pressure being eliminated by conduits l and I in a manner already described in the inventor's copending application Serial No. 334,987 filed January 25, 1929. Air is delivered from chamber I via port II to conduits l2, l3 and I3 and finds its way out through the pair of discharging orifices 3 and 3 adjacent the opposite walls 01 the 'cylinder C to be measured. Variations in the internal diameter of said cylinder C will change the total discharge section adjacent orifices 3 and 3 and modify the reading in manometric branches 4 and l in a manner which will at once be evident.

It will be noted that the manometric readings are instantaneous and continous during movement of exploring element 22 from point to point of cylinder C. It is not necessary to guide element 22 equidistantly from the opposite walls of cylinder C, the variations in pressure being additive and transmitted via conduit l2 to chamber I.

What I claim is:- V

1. An apparatus of the class described, comprising in combination, a source of fluid under substantially constant pressure, achamber communicating with said source, conduit means including an exploring member having a branched passage formed therethrough, the branches of the passage communicating with the atmosphere at the periphery of said exploring member, and means for measuring variation of pressure in said chamber, when said member is introduced between intemal walls of an object, whereby variation in the internal size of said object will be indicated by changes in indications of pressure in said chamber.

2. An apparatus of the class described, comprising in combination, a source of fluid under substantially constant pressure, a chamber communicating with said source, conduit means including an exploring member having a pair of opposed passages formed therethrough, said passages communicating with the atmosphere at the periphery of said exploring member, and means for measuring variation of pressure in said chamber, when said member is introduced between internal walls of an object, whereby variation in the internal size of said object will be indicated by changes in indications of pressure in said chamber.

3. An apparatus of the class described, comprising in combination, a source of fiuid under substantially constant pressure, a chamber communicating with said source, conduit means including a disc having a pair or passages formed therethrough, said passages communicating with the atmosphere at the periphery of said disc, and means for measuring variation of pressure in said chamber, when said disc is introduced between internal opposite walls of an object, whereby variation in the internal size of said object will be indicated by changes in indications of pressure in said chamber. 

